Folding bleacher



May '-7, 1963 G. A. DELF ET AL 3,088,176

FOLDING BLEACHER ATTORNEYS May 7, 1963 G. A. DELF ETAL 3,088,176

FOLDING BLEAGHER Filed May 5, 1960 A 2 Sheets-Sheet 2 0 FIGA.

INVENTORS C-:EORGE A. DLF' ROBERT E. KQRTUM BYCOMM'PMMQQ ATTORNEYS United States Patent ice 3,088,176 Patented May 7 1963 3,083,176 FOLDING BLEACHER George A. Delf, St. Louis, and Robert E. Kortum, Robertson, Mo., assguors to Narragansett Gymnasium Equipment Company, St. Louis, Mo., a corporation of Missouri Filed May 5, 1950, Ser. No. 27,053 9 Ciaims. (Cl. Ztl-1.126)

This invention relates generally to improvements in seating structures, and more particularly to improvements in the construction and operation of bleacher seats `of `the retractile or foldable type especially adapted for use in gymnasiums, auditoriums and the like.

Various types of folding bleacher structures have here- -tofore been proposed for use -in gymnasiums, arenas and similar places where it is desirable to conserve floor space at times while utilizing maximum seating capacity at other times. Although some of the folding `or telescopic bleacher assemblages heretofore proposed have enjoyed a fair degree of commercial success, considerable difficulty has lbeen encountered in providing unitary struc- -tures which are adapted to be folded or telescoped in a simple manner by a single individual without need for special equipment, and which form a neat land compact, substantially enclosed un-it when not in use.

It is an important object of the present invention to provide yan improved retractable bleacher assembly which obviates all of the previously mentioned disadvantages heretofore attendant devices of this general type.

An important objective is to provide an improved unitary bleacher structure having a series of interconnected -seating rows comfortably spaced and `arranged in tiers when extended, and adapted to be quickly and easily telescoped or folded to compact nested -arrangement with a lminimum of eort when desired.

Another important objective is achieved by the provision of improved latching mechanism interconnecting `the telescopically rel-ated seat frames which positively locks the frames in extended position, and which selectively unlocks the frames to permit sequential retraction.

Other important advantages Iare realized in that the latching mechanism is conditioned to enable retraction of the extended frames upon raising ya hinged seat apron on the lowest frame, and the latch interconnecting each adjacent pair of frames is unlocked automatically upon retraction, while lowering the apron allows locking of Asequential operation.

Still another important object is achieved by providing a toggle interconnecting adjacent 'se-ating frames which actuates a latch between its taller associated frame and the next taller adjacent frame incident to movement of its lower associated frame.

Yet another important objective is realized by providing a lever pivotally mounted on the lowest seating frame, one end of which engages a hinged seat rapron and the other end being connected operatively to a latch mechanism between the lowest frame and the next taller frame. Upon lifting the seat apron, the lever acts to unlock the latch when the frames are extended and hence enables retraction, while lowering the apron allows locking of the latch when the frames are moved to their extended arrangement.

Another important object is afforded by providing a spring connected to the lever which tends to urge the lever in a direction to cause unlocking of the latch between the lowest seating frame and the next taller frame automatically upon lifting of the hinged seat apron.

Still another important advantages are realized by providing a stationary stop that is adapted to engage the lever when the lever is disposed in a position as determined by a closed or lowered position of the hinged seat apron on the lowest seat frame when such lowest seat frame is fully retracted relative to the tallest frame, thereby precluding unintentional extension of any seat frame.

An important object is to provide a seating structure that is simple and durable in construction, economical to manufacture, eflicient in operation, and which can be readily manipulated between extended and retracted positions by anyone.

The foregoing and numerous other `objects and vadvantages of the invention will more clearly appear from the following detailed description of a preferred embodiment, particularly when considered in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational View of the seating structure when disposed in a fully retracted position;

FIG. 2 is a side elevational view Vof the seating structure with the lowest seating frame partially extended;

FIG. 3 is a side elevational View of the seating structure fully extended, and

FIG. 4 is a rear elevational view of the seating structure when retracted.

Referring now by characters of reference -to the drawings, and irst to FIGS. l-3 inclusive, it is seen that the seating structure includes a plurality of successive transverse frames indicated at 1t), 11 and 12 of gradually decreasing heights. In the embodiment disclosed, there are a total of three frames, but it will be readily apparent that any suitable number may be utilized depending upon preference and field of usage. The frames 11 and 12 constructed so that they can be selectively nested below and within each adjacent taller frame as is illustrated in FIG. l or be selectively extended as is shown in FIG. 3.

The tallest frame 16 includes a plurality lof laterally spaced base members 13 that normally seat on a subjacent surface such as -a floor. Usually, lthe tallest seating frame 10 is located with its rear against a vertical Wall and the base members 13 extend forwardly therefrom. A plurality of vertically extending posts 14 are attached to and carried by base members 13. Attached lto the posts 14 is a forwardly extending horizontal support 15. Mounted on the top of posts 14 and extending transversely of the frame 1t) is a seat 16 formed by a long plank. Depending from the front edge of top seat 16 -is a seat apron 17 extending transversely of the frame 10.

The tallest frame 1t) is provided with an inverted U-shaped channel 26 that is fixed to the front -of support 15 Vand extends transversely of frame 10 along the top of such support 1S. This channel 20 provides a mounting for the longitudinal seat 21 and its depending yapron 22. For reasons which will later appear, one flange 23 of channel 2@ extends downwardly below the horizontal lsupport 1S fora short distance.

A panel 24 formed by a longitudinal channel is `secured vto posts 14 and extends transversely of frame 10. The panel 24 extends substantially from the bottom edge of seat apron 17 downwardly to the region just `above support 15. The panel 24 cooperates with seat apron 17 to provide a rear closure.

In addition, ya foot rest 25 formed by lan elongate plank is mounted on the forwardly extend-ing horizontal support 15 and is located between the rear panel 24 and the front seat 21.

The middle frame 11 is constructed somewhat similarly to the tallest frame 10 except that it only has a forward seat portion and is constructed of 1a height so that it fits under the horizontal `support 15 of such taller frame 10. More particularly, the middle frame 11 lincludes a plurality Vof laterally spaced base members 26 mounted on rollers 27. The base members 26 are slid-ably related to the adjacent base members 13 of the highest frame 10 and are located inwardly thereof. The rollers 27 enable the middle iframe 11 to be easily land quickly extended or retracted relative yto the adjacent taller frame 10.

Similar to the above structure described with respect to the taller frame 10, the middle frame 11 includes a plurality of upstanding posts 35 mounted on base members 26. As explained previously, the posts 30 extend upwardly to a point just below the horizontal support 15 of the taller frame to enable the middle frame 11 to be telescoped within. The middle frame 11 includes a forwardly extending horizontal support 31 attached to and carried by the posts 30. Annother inverted U-shaped channel 32 is secured to the upper front portion of horizontal support 31 and provides a mounting for a transverse seat 33 and its depending front apron 34. Again, it will be noted that the front ange 35 of channel 32 extends downwardly below the horizontal support 31 to provide a shoulder the purpose of which will be explained subsequently.

A panel 36 extends transversely of middle frame 11 and is secured to the posts 3i), the panel 36 extending upwardly from the support 31 substantially to the bottom margin of seat apron 22 on the taller frame 10 to provide a closure. Attached to the horizontal support 31 is .a transversely extending foot rest 37 located between the panel 36 and the front seat 33.

Of course, the seating structure can be constructed of any number of intermediate seating frames, all of which will be constructed identically with middle frame 11, but of successively and gradually decreasing heights to enable nesting below and within the next adjacent taller frame. Only a single intermediate frame 11 is disclosed in this embodiment for purposes of illustration and clarity.

The lowest seating frame 12 is constructed similar to the intermediate frame 11 with a few modifications. For example, the lowest frame 12 includes a plurality of base members 40 slidably related to and located with the base members 26 of the adjacent taller frame 11. Again, the base members 40 include a plurality of rollers 41 to facilitate extending and retracting the frame 12. A plurality of vertical posts 42 are carried by the rear of base members 40,- the posts 42 terminating just below the horizontal support 31 of the next adjacent taller frame 11. Extending forwardly from posts 42 is a horizontal support 43, the support 43 being attached to upwardly extending posts 44 attached to the front of base members 40.

An langle plate 45 is attached to the horizontal support 43 and is attached to the top of the front posts 44, the angle plate 45 providing a mounting for a transverse seat 46.

Hingedly connected to the front margin of seat 46 is a depending front apron 47. The apron 47 is movable within limits from the closed position shown in full lines in FIG. 3 to the raised position illustrated in broken lines. When in the closed position, the seat apron 47 can be selectively retained in such position by a lock 50.

The lowest seating frame 12 includes .a panel 51 formed by a channel which is attached to and extends between the rear posts 42. The panel 51 extends upwardly from the horizontal support 43'to the lower margin of seat apron 34 on the adjacent taller frame 11. A foot rest 52 is secured to the horizontal support 43 and is located between the panel 51 and the front seat 46.

The latching mechanism between the lowest frame 12 and the next taller frame 11 includes identical mechanism at each side of the seating structure. A detailed descriptionv of the mechanism at one side will suice for the other.

This latching mechanism includes av lever 53 pivotally mounted to the front posts 44. One end 54 of lever 53 engages the back side of seat apron 47 when the apron 47 is in its closed position. The other end 55 of lever 53 is attached to an actuating rod 56 constituting an operating means. The rod 56 is slidably mounted by pins 57 to posts 42 for vertical reciprocating movement within limits upon oscillating movement of lever 53.

A plate 4'60 is attached to posts 42 behind the panel 51 and extends upwardly above and behind the lower depending margin of channel ange 35 to provide an abutment 61. Upon extending the lowest seating frame 12 relative to the next taller trarne 11, the abutment 61 engages the channel flange 35 and limits such extension, and in addition, transmits the outward pulling force to the frame 11 to cause extension of such frame 11 relative to the tallest frame 10.

Cooperating with the -abutment 61 is a latch 62 that is pivotally connected to the horizontal support 31 of the next taller frame 11. When in the relatively extended position of the adjacent pair of frames 11 and 12, the latch 62 rests on top of actuating rod 56 and engages the abutment 61 to preclude relative retraction. When so latched, the rod 56 is in its lowermost position `as determined by the particular disposition of lever 53 when the hinged apron 47 is in its closed position, as is best illustrated in FIG. 3.

A tension spring 63 constituting a reselient means is attached to the horizontal support 43 and is attached to lever 53, the spring 63 tends to pivot the lever 53 in a direction to raise rod 56 toward an unlocked position. Such movement of lever 53 is normally restrained under spring loading by engagement of the hinged seat apron 47 with the lever end 54.

To release the l-atching means interconnecting the lowest frame 12 and the adjacent taller frame 11, and hence permit relative retraction, the hinged apron 47 is raised as is illustrated in broken lines in FG. 3. The lever 53 is thereby released and the spring 63 causes the lever to raise actuating rod 56 upwardly so that rod 56 lifts the latch 62 above the abutment 61. The frames 11 and 12 are now unlocked and can be relatively retracted by rolling the lowest frame 12 inwardly below the next taller frame 11.

The locking mechanism interconnecting the next adjacent pair of frames 10 and 11 includes a latch 64 pivoted to the forwardly extending horizontal support 15. A plate 65 is secured to vertical posts 30 behind the panel 36, the plate 65 including an abutment 66 that is adapted to engage the depending lower margin of channel ange 23 to limit relative extension of frames 10 and 11, and which is adapted to engage the latch 64 when the frames 10 and 11 are extended so as to preclude relative retraction. An actuating rod 67 constituting operating means is slidably mounted by pins 68 to the posts 30 for reciprocating movement within limits.

When the frames 10 and 11 are relatively extended, the latch 64 rests on top of actuating rod 67 and engages the abutment 66 to prevent relative retraction. The rod 67 is lowered to one limit as is illustrated in FIG. 3 by gravity to retain the latch 64 .as described.

A toggle 70 consisting of pivotally interconnected arms 71 and 72 is located at opposite sides of the frame 11.V

The toggles 70 are interconnected by transverse equalizing bars 73 and 74, bar 73 interconnecting the toggle arms 71 and bar 74 interconnecting toggle arms 72. The toggle arm 71 is pivotally connected to the rear vertical posts 42 of the lowermost frame 12 while the other toggle arm 72 is pivotally connected to the horizontal support 31 of the next taller frame 11.

Upon release of latch 62 and subsequent retraction of -lower-most frame 12 relative to the next adjacent taller frame 11, the toggle 70 at each side of the seating structure rotates to engage the actuating rod 67. More particularly, the toggle arm 72 moves upwardly to engage the lower end of yrod 67 and operates to raise the rod 67 to lift latch 64 out of the path of abutment 66. This unlatching operation occurs substantially upon complete retraction of the lowermost frame 12 within the next taller frame 11, and hence conditions the frame 11 for retraction within the next taller frame 10. It is seen that this -mechanism .provides for sequential retraction of the seating frames.

A pair of toggles 75 operatively interconnects the adjacent frames and 11, one of the toggles 75 being located at each side of the seating structure. Each toggle 75 includes pivotally interconnected arms 76 and 77. Toggle arm 76 is pivotally connected to the horizontal support of the tallest frame 10 while the other toggle arm 77 is pivotally connected to the posts 30 of the next lower frame 11. Equalizing bars 80 and 81 extend transversely between and interconnect the toggles 75 at opposite sides of the seating structure. More particularly, bar 80 operatively interconnects toggle arms 76 while bar 81 operatively interconnects arms 77.

lt is an important function of the equalizing bars 73 and 74 interconnecting toggles 70 and of equalizing bars 80 and 81 interconnecting toggles 75 to transmit equal forces to the opposite sides of the frames when being retracted or extended, thus assuring that the frames will move in a straight path without any binding action therebetween, such as would occur if the frames could be cocked laterally.

Lock means is provided to retain the frames in their fully retracted position as is illustrated in FIG. l. An angle plate 82 constituting a fixed stop is secured to the door immediately below lever 53. An arm 83 is attached to lever 53 and extends downwardly to interiit behind angle plate 32 when the lever 53 is pivoted upon closing the front seat apron 47. This action locks all of the frames in the retracted position. To release the frames, the hinged front apron 47 is raised and the lever 53` is automatically pivoted under the loading of tension spring 63 so that lever arm 83 is raised above the angle plate 82. The lowest frame 12 can then be extended relative to the next taller frame 11.

It is thought that the operation and functional advantages of the seating structure have become fully apparent from the foregoing detailed description of parts, but for completeness of disclosure the extension and retraction of the frames will be briey described. It will be assumed that the frames are relatively retracted and locked in such position, as is illustrated `in FIG. 1, `and that it is desired to extend the frames to provide an operative seating structure.

First, the lock 50 is unlocked to release the hinged front apron 47. Upon lifting of seat apron 47, as illustrated in FIG. 2, the lever 53 is moved pivotally by spring 63 so that lock arm 83 clears angle plate 82 and so that actuating rod 56 raises latch 62 to clear the abutment 61. The frame 12 can then be relatively extended with respect to the next taller trame 11.

As the lowest frame 12 is extended, the latch 62 rides over the abutment 61 and drops down upon actuating rod 56, the rod 56 being `lowered by hingedly closing the seat apron 47. In this position, the latch 62 engages the abutment 61 to preclude relative retraction of frames 11 and 12, and in addition, the abutment 61 engages the lower margin of channel ange 35 to exert an outward pulling force on the taller frame 11.

As the intermediate frame 11 is extended relative to the next taller frame 10, substantially the same action takes place. lFor example, the latch 64 rides over the abutment 66 and drops down on top of the actuating rod 67, the rod 67 being lowered .because the toggle 70l has been moved out of the collapsed position upon relative extension of the frames 11 and 12. Furthermore, the abutment 66 engages the lower margin of channel flanges 23 to determine the fully extended position.

When the frames 16, 11 `and 12 are fully extended, and with the hinged seat apron 47 closed, the latches 62 and 64 preclude unintentional retraction. The hinged seat apron 47 can then be locked in its closed position by lock 50 if desired.

To retract the seating frames from their fully extended position, the front seat apron 47 is unlocked by lock 50 and hingedly raised. The lever 53 is pivoted under the loading of spring 63 to lift the actuating rod 56, and hence lift the latch 62 above the abutment 61. The lowest frame 12 can then be relatively retracted within the next taller frame 11. When frame 12 is fully retracted within the adjacent frame 11, the toggle 70 engages the actuating rod 67 to lift the l-atch 64 above the abutment 66. Then, the frames 11 and 12 as a unit may be retracted relative to the adjacent taller frame 10. When fully retracted, the hinged apron 47 is closed so that the lever arm 83 tits behind the angle plate 82 to lock the frames in the retracted position. 1f desired, the hinged apron 47 can be retained in closed position by lock 50.

It is seen that the particular structure causes sequential operation of the interconnected seating frames upon being either extended or retracted. Furthermore, it is seen that operation of the frames is controlled by a hinged seat apron 47 on the lowest frame 12 and that movement of each frame conditions the next taller frame for either retraction or extension.

Although the invention has been described by making detailed reference to `a single preferred embodiment, such detail is to be understood in an instructive, rather than in any restrictive sense, many variants being possible within the scope of the claims hereunto appended.

We claim as our invention:

l. In a seating structure, a plurality of transverse frames of decreasing heights, the lower frame being retractable toward or extensible from the next taller frame, an abutment on the lower frame, a latch movably mounted to the next taller frame and engaging the abutment when the frames are extended to preclude retr-action, a lever pivoted to said lower frame, means hinged to the lower frame and engaging one end of said lever, and an operating means operatively connected to the other end of said lever and mounted on said lower frame for movement within limits, the said latch being disposed in the path of said abutment to preclude retraction of said frames with the operating means in one limit, the operating means in another limit holding the said latch out of such path to enable retraction, said lever moving the operating means to said limits in response to movement of said hinged means.

2. ln a seating structure, a plurality of transverse trames of decreasing heights, the lower -frame being retractable toward or extensible from the next taller frame, an abutment on the lower frame, a latch movably mounted to the next taller frame and engaging the abutment when the frames are extended, a lever pivoted to said lower iframe, an actuating rod connected to one end of said lever and slidably mounted on said lower 'frame for movement within limits, the latch being disposed in the path of said abutment to preclude retraction of said frames with the actuating rod in one limit, the rod in another limit holding the latch out of such path to enable retraction, an apron hinged to said lower frame and engaging the other end of said lever, resilient means connected to said lever tending to pivot the lever in a direction to move the actuating rod to the said other limit to unlock said latch, said hinged apron in one position `moving the lever so that the said latch is locked, and said apron in another position enabling the lever to pivot under loading of said resilient means so that the said latch is unlocked by said actuating rod.

3. In a seating structure, a plurality of transverse frames of decreasing heights, the lower frame being retractable toward or extensible from the next taller frame, an abutment on one of said frames, a latch movably mounted to the next adjacent yframe and engaging the abutment when the frames are extended, a lever pivoted to said lower frame, an operating means connected to one end of said lever and mounted on said lower frame for movement within limits, the latch engaging the abutment to preclude retraction of said frames with the operating means in one limit, the operating means in another limit disengagingthe latch from the Vabutment to enable retraction, resilient :means connected to said lever Ytending to 'Pivot the lever in adirection to move the operating means to the said other limit to unlock said latch, an apron hinged to the lower frame and engaging the lever, said hinged apron in one position holding the lever so that the said latch is locked, and said apron in another position enabling the llever to pivot under loading of said resilient means so that the said latch is unlocked by said operating means, a stop element on said lever, a xed stop shoulder, the stop element engaging the said stop shoulder when the frames are fully retracted and the apron is moved to said one position in which the said latch is normally locked so as to prevent extension of .said frames.

4. `In a seating structure, a plurality of transverse frames of successively decreasing heights, said frames being retractable in nested relation within and below the next taller frame and successively extensible therefrom, a latch movably mounted to each frame except the lowest frame, an abutment on each frame except the tallest frame engaging the latch on the next taller frame when the frames are extended so as to prevent retraction, means hinged to the lowest yframe and movable within limits, means operatively interconnecting the said hinged means with the latch on the next taller frame for moving the said latch out of locking relation to the abutment on said lower Iframe upon movement of said hinged means to one of said limits, a toggle interconnecting each pair of adjacent frames, and means engageable by said toggles to move said other latches out of locking relation to their associated abutments as the yframes are sequentially retracted, the retraction of each -frame conditioning the next taller frame for retraction yby unlocking the latch normally holding said next taller frame.

5. In a seating structure, a plurality of transverse frames of successively decreasing heights, said frames being retractable in nested relation to the next taller frame and successively extensible therefrom, a latch movably mounted to each Iframe except the lowest frame, an abutment on each frame except the tallest frame engaging the latch on the next taller -frame when the frames are extended so as to prevent retraction, operating means movably mounted on each frame except the tallest frame Vand engaging the latch on the next taller frame, means hinged to the lowest frame and movable within limits, means operatively interconnecting said hinged means with the said operating means on the lowest -frame for moving the latch associated with such operating means out of locking relation to the abutment `on the lowest frame upon :movement of said hinged means to one of .said limits, and a toggle interconnecting each pair of adjacent frames, each toggle engaging the operating means :of its taller asociated Iframe to move the latch of the next ta-ller frame out of locking relation to its associated :abutment as its lower associated frame is selectively re- '.tracted, the retraction of each -frame conditioning the :next taller frame for retraction by unlocking the latch normally holding said next taller frame.

6. In a seating structure, a plurality of transverse frames fof successively decreasing heights, each said frame being :retractable in nested relation to the next taller frame and :selectively extensible therefrom, latching means interconnecting each adjacent pair of frames when the frames :are extended so as to prevent retraction, means hinged to the lowest frame and movable within limits, means operatively interconnecting said hinged means with the said latching means interconnecting the lower pair of adjacent frames yfor unlocking such latching means upon movement of said hinged means to one of said limits, a toggle interconnecting each adjacent pair of -fra-mes, and means associated with each other latching means and lselectively engageable by said toggles for unlocking said other latching means as the frames are retracted, the retraction of each frame conditioning the next taller frame f or retraction by unlocking ,the latching means normally holding said next taller yframe. Y

7. Aln a `seating structure, a plurality of transverse frames of successive.y decreasing heights, said frames ybeing retractable inne'stedrelation to the next taller frame and selectivelyV extensible therefrom, a latch pivotally mounted to each frameexcept the lowest frame, an abutment on each frame except the tallest frame engaging the latch on the next taller frame when the frames are extended so as to prevent retraction, a seat apron hinged to the lowest frame and movable within limits, an actuating rod slidably mounted on each frame except the tallest frame and engaging the latch on the next vtaller frame, a lever operatively interconnecting said hinged apron with the said actuating rod on the lowest frame for moving the latch associated with such rod out of locking relation to the abutment on the lowest frame upon 4movement of said hinged apron to one of said limits, and a toggle interconnecting each pair of adjacent frames, each toggle engaging the rod of its taller associated frame to move ,the latch of the next taller frame out of locking relation to its abutment as its lower associated frame is selectively retracted, the retraction of each frame conditioning the next taller frame for retraction by unlocking the latch normally holding `said next taller frame.

8. In a seating structure, a plurality of transverse frames of decreasing heights, each frame including a seat on the front of said frames, an apron extending downwardly from each seat, a panel at the rear of said frames extending :upwardly to the apron of the next taller frame when the frames are extended, and a foot rest mounted between the seat and panel, the llower frame being retractable within and below the taller frame and selectively extensible therefrom, a latch movably mounted to each frame except the lowest frame, an abutment on each frame except the tallest frame engaging the latch on the next taller frame when the frames are extended so as to prevent retraction, operating means movably mounted on each frame except the tallest frame and engaging the latch on the next taller frame, means hinged to the lowest frame and movable within limits, means .operatively interconnecting said hinged means with the said operating means on the lowest frame 'for moving the latch associated with such operating means out of locking relation to the abutment on the lowest frame upon movement of said hinged means to one of said limits, and a toggle interconnecting each pair of adjacent lframes, each toggle engaging the operating means of its taller associated frame to move the latch of the next taller frame out of locking relation to its abutment as the toggles lower associated frame is selectively retracted, the retraction of each frame conditioning the next taller frame yfor retraction -by unlocking the latch normally holding the said next taller frame.

9. In a seating structure, a plurality of transverse frames of decreasing heights, each frame including a seat on the front of said frames, an apron extending downwardly from each seat, a panel at the rear of said frames extending upwardly to the apron of the next taller frame when the yframes are extended, and a foot rest mounted between the seat and panel, the lower frame being retractable within and below the taller frame and selectively extensible therefrom, a latch movably mounted to each frame except the lowest frame, an abutment on each frame except the tallest frame engaging the latch on the next taller frame when the frames are extended so as to prevent retraction, a shoulder on each frame except the lowest frame engaging the abutment of the next taller frame when the lower frame is extended so as to enable extension of the said next taller frame, an actuating rod slidably mounted -for reciprocation on each frame except the tallest frame and engaging the latch on the next taller frame, a lever pivoted to the lowest frame, the apron on the lowest frame being hinged and engaging one end of said lever, the actuating rod on the lowest yframe being operatively connected to the other end of said lever, said lever moving the latch associated with the 4last said rod out of locking relation to the abutment on the lowest `frame upon movement of said hinged apron, a spring connected to said lever tending to pivot the lever in a direction to move the last said rod to one limit to unlock said latch, and a toggle interconnecting each pair of adjacent frames, each toggle engaging the actuating rod of its associated taller frame to move the latch of the next taller frame out of locking relation as its associated lower frame is selectively retracted.

OTHER REFERENCES Safway Spectator Seating, pp. 4 and 5, catalog No. GS-657 of Safway Steel Products, Inc., Milwaukee 13, Wis. 

4. IN A SEATING STRUCTURE, A PLURALITY OF TRANSVERSE FRAMES OF SUCCESSIVELY DECREASING HEIGHTS, SAID FRAMES BEING RETRACTABLE IN NESTED RELATION WITHIN AND BELOW THE NEXT TALLER FRAME AND SUCCESSIVELY EXTENSIBLE THEREFROM, A LATCH MOVABLY MOUNTED TO EACH FRAME EXCEPT THE LOWEST FRAME, AN ABUTMENT ON EACH FRAME EXCEPT THE TALLEST FRAME ENGAGING THE LATCH ON THE NEXT TALLER FRAME WHEN THE FRAMES ARE EXTENDED SO AS TO PREVENT RETRACTION, MEANS HINGED TO THE LOWEST FRAME AND MOVABLE WITHIN LIMITS, MEANS OPERATIVELY INTERCONNETING THE SAID HINGED MEANS WITH THE LATCH ON THE NEXT TALLER FRAME FOR MOVING THE SAID LATCH OUT OF LOCKING RELATION TO THE ABUTMENT ON SAID LOWER FRAME UPON MOVEMENT OF SAID HINGED MEANS TO ONE OF SAID LIMITS, TOGGLE INTERCONNECTING EACH PAIR OF ADJACENT FRAMES, AND MEANS ENGAGEABLE BY SAID TOGGLES TO MOVE SAID OTHER LATCHES OUT OF LOCKING RELATION TO THEIR ASSOCCIATED ABUTMENTS AS THE FRAMES ARE SEQUENTIALLY RETRACTED, THE RETRACTION OF EACH FRAME CONDITIONING THE NEXT TALLER FRAME FOR RETRACTION BY UNLOCKING THE LATCH NORMALLY HOLDING SAID NEXT TALLER FRAME. 